1. Field of the Invention
The invention relates to a window screen for sliding sash windows and is characterized by the fact that the screen rolls in a coil but does not require the use of spring wound rollers of the type used on conventional window shades. Strips of coil spring material are bonded to or extend along the surface of the screen and provide the force which winds the screen when the sash with which it is associated is lowered.
2. Description of Related Art
Heretofore, roller window screens have required mechanical interaction at their edges to manage their coiling and uncoiling. They have been propelled from without. Even a roller shade mechanism type, while physically occupying the core of the roll, requires an edge mounted bracket held in fixed relationship to the window-frame for its propulsion. There are many such prior structures shown in U.S. Pat. Nos. such as 609,134; 2,553,868, 2,605,823; 2,825,400 and 3,470,934. U.S. Pat. No. 1,164,383 shows tapes alongside the screen, but such tapes are for reinforcement and do not function as springs to rewind the screen. U.S. Pat. No. 2,462,520 shows perforated bands along the side edges of the screen which are wound and unwound by rowels on spring wound rollers attached to the window frame.